Supplemental Oil and Gas Reserve Information (Details 3)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Oil
Average Sales Price and Production Costs Per Unit of Production [Line Items]
Average sales price	90.48	94.88	90.45
Natural Gas Liquids
Average Sales Price and Production Costs Per Unit of Production [Line Items]
Average sales price	31.54	31.63	43.74
Natural Gas
Average Sales Price and Production Costs Per Unit of Production [Line Items]
Average sales price	4.27	3.59	3.70